CARRYING CAPACITY STUDY OF TEESTA BASIN IN SIKKIM Principal Investigator Prof. (Mrs.) Pramila Goyal CENTRE FOR ATMOSPHERIC SCIENCES INDIAN INSTITUTE OF TECHNOLOGY, DELHI HAUZ KHAS, NEW DELHI-110016 PARTICIPATING INSTITUTIONS • Centre for Inter-disciplinary Studies of Mountain & Hill Environment, University of Delhi, Delhi • Centre for Atmospheric Sciences, Indian Institute of Technology, Delhi • Centre for Himalayan Studies, University of North Bengal, Distt. Darjeeling • Department of Geography and Applied Geography, University of North Bengal, Distt. Darjeeling • Salim Ali Centre for Ornithology and Natural History, Anaikatti, Coimbatore • Water and Power Consultancy Services (India) Ltd., Gurgaon, Haryana • Food Microbiology Laboratory, Department of Botany, Sikkim Government College, Gangtok VOLUMES INDEX* Volume – I INTRODUCTORY VOLUME Volume – II LAND ENVIRONMENT - GEOPHYSICAL ENVIRONMENT Volume – III LAND ENVIRONMENT - SOIL Volume – IV WATER ENVIRONMENT Volume – V AIR ENVIRONMENT Volume – VI BIOLOGICAL ENVIRONMENT TERRESTRIAL AND AQUATIC RESOURCES Volume – VII BIOLOGICAL ENVIRONMENT - FAUNAL ELEMENTS Volume – VIII BIOLOGICAL ENVIRONMENT - FOOD RESOURCES Volume – IX SOCIO-ECONOMIC ENVIRONMENT Volume – X SOCIO-CULTURAL ENVIRONMENT EXECUTIVE SUMMARY AND RECOMMENDATIONS *For Volume-wise Detailed Index – Refer to the end of the report PREFACE Rapid urbanization and industrialization has changed the whole scenario of urban cities. Hence it became necessary that alternative to further growth of these cities should be identified, which is consistent with the objectives of economic growth and social development. A city cannot have infinite carrying capacity and sustainable development can be achieved only if the development is within the carrying capacity of the region. This carrying capacity study, accordingly, covers the analysis of supportive as well as assimilative capacities to ensure sustainable development of the region. At the instance of the Ministry of Environment and Forests (MoEF), a study on “Carrying Capacity of Teesta Basin in Sikkim” has been initiated with financial assistance from National Hydroelectric Power Corporation (NHPC) in view of a series of hydro-power development schemes envisaged in the Teesta Basin and is being undertaken by the Centre for Inter-disciplinary Studies of Mountain and Hill Environment (CISMHE), University of Delhi. The scope of the study, inter-alia, includes. Assessment of supportive and assimilative capacities. Optimization of resource allocation strategy. Evaluation of state development plan as well as business as usual scenario. Preparation of short and long term action plans to be implemented by concerned agencies through technological and policy planning interventions. Development of alternate scenarios including prioritization of preferred scenarios. The Indian Institute of Technology Delhi was entrusted with the task of preparing a sustainable development model of Sikkim through assimilative capacity of air environment which will be useful for carrying capacity planned development in the state. The main activities of IIT Delhi are the estimation of assimilative capacity of air resources for most critical environmental areas in Teesta basin and to develop and validate air quality models for Sikkim. The present study includes the monitored air quality at different locations and the emission inventory of air resources based on secondary data acquired from different sources which are used to estimate assimilative capacity of air environment. Assimilative capacity of air environment is the maximum amount of pollution load that can be discharged without violating the best designated use of the air resource in the planning region. The phenomena governing the assimilative capacity of air environment include dilution, dispersion and deposition. The air pollution assimilative potential of an airshed can be estimated as the ventilation coefficient for the area. The ventilation coefficient is an indicator of horizontal as well as vertical mixing potential. Estimation of assimilative capacity for an environment involves: Delineation of an airshed based on topography of the area and identification of micro-climatic zones depending topography and wind fields data, preparation of inventory and quantification of pollution loads. The assimilative capacity of Sikkim has been estimated by pollution potential, which has been estimated by using dispersion models in terms of concentration of pollutants, and is inversely proportional to the assimilative capacity of the atmosphere. Dispersion models for point, area and line sources have been used to predict the spatial and temporal distribution of three pollutants namely sulphur dioxide (SO2), suspended particulate matter (SPM) and oxides of nitrogen (NOX). These models have been validated against the observed data. Predictions of temporal and spatial variations in air pollutants concentrations for existing sources using multiple source-receptor model to establish source-receptor relationship. Upper limits of pollution load have been established in critical pockets, after comparing with standards. The trust reposed by the Ministry of Environment and Forests (MoEF) in the Centre for Atmospheric Sciences (CAS), IIT Delhi for awarding of this challenging project is gratefully acknowledged. The cooperation and advice provided by Prof. M.K. Pandit and Dr. Arun Bhaskar (CISHME) deserve special thanks. Coordinator also wishes to thank Mr. Sankalp Anand and Mr. Bharat Pradhan, CAS, IIT Delhi for their contribution to the study. (Prof. Pramila Goyal) (Coordinator) CONTENTS Page No. CHAPTER 1 CARRYING CAPACITY BASED DEVELOPMENT PLANNING PROCESS 1.1 INTRODUCTION 1 1.1.1 Concept of Carrying Capacity 2 1.1.2 Framework for Carrying Capacity Based 2 Development Planning 1.1.3 Assimilative Capacity Dimensions of Air Environment 3 1.1.4 Resource Allocation Strategies 3 1.2 THE STUDY AREA – SIKKIM 4 1.2.1 Brief History of Sikkim 6 1.2.2 Physical Features 7 1.2.3 Climate 8 1.2.4 Temperature 11 1.2.5 Rainfall 11 1.2.6 Winds 12 1.2.7 Population 12 1.3 OBJECTIVES 13 1.4 ASSIMILATIVE CAPACITY ASSESSMENT 14 METHODOLOGY CHAPTER 2 APPROACH I- ESTIMATION OF ASSIMILATIVE CAPACITY THROUGH VENTILATION COEFFICIENT 2.1 INTRODUCTION 15 2.2 METHODOLOGY AND DATA REQUIREMENT 17 2.2.1 Mixing /Inversion Height data 17 2.2.2 Sodar Measurement 17 2.2.3 Site Characteristics 18 2.2.4 Sodar Characteristics 19 2.3 RESULTS 20 CHAPTER 3 APPROACH II- ASSESSMENT OF POLLUTION POTENTIAL USING AIR QUALITY MODELING 3.1 AIR QUALITY STUDIES USING MODELS 22 3.2 BASELINE ENVIRONMENTAL QUALITY OF AIR 23 3.2.1 Identification of Air Quality Impacts of a 24 Proposed Project 3.2.2 Compilation of Air Quality Data 24 3.2.3 Emission Inventory 25 3.2.4 Methods of Emission Estimation from 26 Vehicular Traffic 3.3 MODEL DESCRIPTION 28 3.4 NORTH SIKKIM 31 3.4.1 Study Area: Chungthang and its Surrounding Areas 31 3.4.2 Sources of Air Pollution in the Region 32 3.4.3 Emission Inventory of Chungthang 34 3.4.4 Emission of Line Source 34 3.4.5 Emission of Area source 36 3.4.6 Results 36 3.4.7 Conclusions 37 3.5 SOUTH AND EAST REGIONS OF SIKKIM 37 3.5.1 Emission Inventory 37 3.5.2 Results 38 3.6 GANGTOK 40 3.6.1 Emission Inventory 40 3.6.2 Results 41 3.6.3 Conclusions 45 3.7 WEST SIKKIM 48 3.7.1 Sources of pollution in West Sikkim 48 3.7.2 Emission Inventory 48 3.7.3 Results 49 CHAPTER 4 AIR QUALITY ASSESSMENT OF TEESTA RIVER BASIN IN SIKKIM 4.1 INTRODUCTION 52 4.2 METHODOLOGY 53 4.3 RESULTS 54 4.4 CONCLUSIONS 54 BIBLIOGRAPHY 56 ANNEXURE – Report on Inversion/ Mixing Height Studies at G.B. Pant Institute of Himalayan Environment & Development, Gangtok Sikkim LIST OF TABLES Table 3.1 Emission rate of air pollutants Table 3.2 Source strength of pollutants Table 3.3 Vehicular traffic at 4 different points in Gangtok during peak hour Table 3.4 Vehicular traffic at 4 different points in Gangtok during non-peak hour Table 3.5 Secondary data of emission factor for vehicular source Table 3.6 Statistical errors computed for both the models IITLS and Caline-3 LIST OF FIGURES Figure 1.1 Map showing districts of Teesta basin in Sikkim Figure 2.1 Various Sodar structure observed at G.B. Pant Institute, Pangthang, Sikkim Figure 2.2 Diurnal variation of ventilation coefficient, mixing height & wind speed at Gangtok Figure 3.1 Map showing North Sikkim district Figure 3.2 Gridded source inventory of North Sikkim Region Figure 3.3 Spatial variation of pollutants in North Sikkim Figure 3.4 Map showing South and East Sikkim districts Figure 3.5 Gridded source inventory covering South-East region of Sikkim Figure 3.6 Concentration of pollutants in East and South region of Sikkim (Caline-3) Figure 3.7 Variation of concentration of pollutant in East and South region of Sikkim by using IITLS model Figure 3.8 Temporal variations of pollutants for East and South Sikkim (Caline-3) Figure 3.9 Temporal variations of pollutants for East and South Sikkim (IITLS) Figure 3.10 Gridded source inventory of Gangtok Figure 3.11 Graph showing increase in the no. of vehicles from 1994 to 2004 Figure 3.12 Comparison of model evaluated concentration with the observed values at Gangtok Figure 3.13 Temporal variations of pollutants by using IITLS Model at Gangtok in December Figure 3.14 Temporal variations of pollutants by using IITLS Model at Gangtok in April Figure 3.15 West Sikkim: Sources (links) and Receptors Figure 3.16a Variation of pollutants concentration during summer Figure 3.16b Variation of pollutants concentration during winter Figure 3.17 Temporal variation of concentration in West Sikkim in January 2001 Figure 3.18 Temporal variation of concentration in West Sikkim in April 2001 Figure 3.19 Temporal variation of concentration in West Sikkim in April 2004 Figure 3.20 Temporal variation of concentration in West Sikkim in January 2004 Figure 4.1 Isopleths of Sikkim Figure 4.2 Isopleths of Sikkim Figure 4.3 Isopleths of Sikkim Figure 4.4 AQI of Sikkim 1.1 INTRODUCTION Urban areas are characterized by high population density and economic development.